<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			.father {
				width: 800px;
				height: 400px;
				background-color: pink;
				margin: 40px auto;
				position: relative;
			}
			.son {
				width: 100px;
				height: 40px;
				background-color: purple;
				position: absolute;
				left: 50%;
				margin-left: -50px;
				top: 50%;
				margin-top: -20px;
			}
		</style>
	</head>
	<body>
		<div class="father">
			<div class="son"></div>
		</div>
	</body>
</html>
